Consuming foods high in fiber may help lower gut inflammation and support beneficial bacteria that protect against harmful pathogens, according to a recent study.
Key Takeaways:
- A diet rich in fiber nourishes beneficial gut bacteria, which play a role in defending against infections from bacteria such as E. coli.
- These beneficial microbes break down fiber into short-chain fatty acids, which have anti-inflammatory properties and help strengthen the gut barrier.
- Short-chain fatty acids also help prevent harmful bacteria from thriving by outcompeting them, reducing the risk of serious infections.
A diet rich in fiber from foods such as vegetables, beans, and whole grains may play a crucial role in reducing gut inflammation and preventing infections caused by harmful bacteria. New research highlights how fiber supports the growth of beneficial gut bacteria, which in turn helps maintain digestive health and protect against common pathogens.
How Fiber Supports Gut Health
The link between dietary fiber and gut health has been well established, with numerous studies demonstrating that fiber acts as a key nutrient for beneficial gut bacteria. These microbes ferment fiber into short-chain fatty acids (SCFAs), which help maintain the integrity of the gut lining and reduce inflammation.
“Previous work has shown that fiber is converted by gut bacteria into chemicals known as short-chain fatty acids, and these in turn can have a variety of health benefits such as reducing inflammation and maintaining the integrity of the gut barrier,” explains Alexandre Almeida, Ph.D., senior study author and researcher at the University of Cambridge’s Department of Veterinary Medicine in England.
This protective effect could have significant implications for reducing the risk of infections. “We found that short-chain fatty acids showed the strongest protective signal [against the risk of infections], suggesting that fiber consumption could have a positive effect in this context,” Almeida adds.
How Fiber Helps Prevent Harmful Bacteria from Spreading
The study suggests that fiber not only supports beneficial bacteria but also plays a role in suppressing harmful microbes. In particular, fiber may help limit the spread of bacteria from the Enterobacteriaceae family, which includes Klebsiella pneumoniae (a leading cause of pneumonia and meningitis), Shigella, and E. coli. While these bacteria exist naturally in the gut at low levels, an overgrowth can increase the risk of severe infections.
To investigate this further, researchers conducted a large-scale computational analysis of gut microbiome samples. By examining more than 12,000 stool samples from individuals across 45 countries, the study identified key bacterial species that flourish in fiber-rich environments. One of the most prominent was Faecalibacterium, a beneficial genus linked to anti-inflammatory effects.
Published in Nature Microbiology, the study concluded that microbiome composition could predict whether a person’s gut was more or less likely to harbor disease-causing bacteria. The presence of Faecalibacterium and other beneficial microbes appeared to correlate with a lower likelihood of harmful bacterial colonization.
For Mahmoud Ghannoum, Ph.D., a microbiome scientist and professor at the Case Western Reserve University School of Medicine Digestive Health Research Institute in Cleveland, the findings reinforce previous research on fiber’s prebiotic role in maintaining gut balance.
“By using new AI technology and analyzing a large sample of humans, this study lends support for the concept that we should adopt a diet that has fiber to rebalance and maintain our healthy microbiome,” says Dr. Ghannoum, who was not involved in the research.
Probiotic Supplements May Not Be the Best Solution
The research also raises questions about the effectiveness of probiotic supplements. While probiotics introduce specific strains of beneficial bacteria into the gut, the study suggests they may not be enough to counteract harmful microbes.
“If we want to make a positive change to our gut microbiome, it may be more effective to facilitate the growth of a wide range of good bacteria — for instance through diet — than to introduce any one particular set of species [of bacteria] through probiotics,” says Almeida.
Although probiotic supplements are widely marketed for gut health, there is still a lack of conclusive evidence proving they provide long-term benefits. Instead, many experts recommend eating naturally probiotic-rich foods, such as fermented products, to support microbiome diversity.
According to Julia Zumpano, RD, a registered dietitian with the Cleveland Clinic Center for Human Nutrition, probiotic foods that may improve gut bacteria include:
- Sauerkraut
- Kimchi
- Miso
- Kefir
- Yogurt
- Kombucha
How to Increase Fiber Intake
Eating a diverse, fiber-rich diet is one of the most effective ways to support beneficial gut bacteria. Zumpano, who was not involved in the study, highlights several key food groups that are excellent sources of fiber:
Fruits – Berries, bananas, apples, pears, avocados, and kiwi.
Vegetables – Dark leafy greens, artichokes, broccoli, Brussels sprouts, cabbage, cauliflower, and turnips.
Legumes – Lentils, chickpeas, black beans, kidney beans, and pinto beans.
Whole grains – Quinoa, wild rice, farro, buckwheat, and oats.
At the same time, reducing processed and refined foods is essential to maintaining gut health. Many ultra-processed foods contain little to no fiber, which can disrupt the gut microbiome by depriving beneficial bacteria of essential nutrients. Foods that are typically low in fiber and may negatively impact gut health include:
- Processed meats
- Baked goods
- Fried and fast food
- Sweets and desserts
- Soda and sugary drinks
- Processed fats like margarine and shortening
More Research Needed on Fiber’s Role in Infection Prevention
Although the findings provide strong evidence of fiber’s positive impact on gut health, Almeida cautions that further research is necessary to determine the long-term effects. The study was observational, meaning it analyzed the gut microbiome at a single point in time rather than over an extended period.
“This means that future work is needed to experimentally test whether certain things like fiber and other nutrients directly prevent the incidence of infections in a longer time span,” Almeida explains.
Additionally, the study highlights an urgent need to explore new strategies for preventing bacterial infections, particularly in light of rising antibiotic resistance. Klebsiella pneumoniae, for example, is increasingly developing resistance to common antibiotics, making infections more difficult to treat.
“With higher rates of antibiotic resistance, there are fewer treatment options available to us,” Almeida warns. “The best approach now is to prevent infections from occurring in the first place, and we can do this by reducing the opportunities for these disease-causing bacteria to thrive in our gut.”
Final Thoughts
The growing body of research on gut health emphasizes the importance of diet in shaping the microbiome. Fiber-rich foods not only nourish beneficial bacteria but also help suppress harmful microbes that could lead to infections. While probiotic supplements may have some benefits, the study suggests that a balanced, fiber-filled diet is a more effective long-term strategy for gut health.
As experts continue to investigate the role of the microbiome in disease prevention, one message remains clear: what we eat plays a significant role in our overall health. By incorporating more fiber into daily meals and reducing processed foods, individuals can take a proactive approach to supporting a healthy gut and strengthening their body’s natural defenses against infections.